Definition of Cancer
Defination of Cancer:- Cancer is a group of disease characterized by the uncontrolled growth and division of abnormal cells, which can invade nearby tissues and spread ( metastasize ) to other parts of the body through the blood or lymphatic systems.
Standard Medical Defination:-
A common defination from the National Cancer Institute states “ Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body “ .This contrasts with benign tumors ,which do not invade or metastasize.
Biological Characterestics
Biological Characterestics :- Cancer arises from genetic mutations disrupting normal cell regulation, leading to hallmarks like sustained proliferation, evasion of cell death and angiogenesis ( new blood vessel formation to feed tumors) . Cells transform through accumulated changes ,becoming malignant.
Major Types
Carcinoma:- From epithelial tissues e.g. Skin, Organs.
Sarcoma:- From connective tissues e.g. Bone , Muscle.
Leukemia:- Blood -forming tissues.
Lymphoma :- Immune system cells.
Main Types Of Cancer With Brief Descriptions
Cancer refers to a group of diseases involving uncontrolled cell growth. Here are some of the main types, grouped by common categories ,with brief descriptions:
A) Carcinomas (From epithelial Tissues)
The most common type 80% to 90% of cases ,arising from epithelial cells lining organs and glands;includes adenocarcinoma and squamous cell carcinoma like skin ,lungs, esophagus.
Breast Cancer:- Starts in breast tissue cells; often detected via mammograms; affects women mostly but men too.
Lung Cancer:- Originates in lung lining ;strongly linked to smoking; includes non-small cell and small cell subtypes.
Prostate Cancer:- Develops in prostate gland (Men) ; usually slow-growing ;screened viaPSA tests.
Colorectal Cancer:- Forms in colon or rectum lining ;linked to diet , polyps; preventable via colonoscopy.
B) Sarcomas (from connective tissues like Bone , Muscle.)
these are rare cancer,1% from mesenchymal tissues like bone,cartilage,fat,muscle,or blood vessels ;example include osteosarcoma (bone) and leiomyosarcoma ( smooth muscle).
- Osteosarcoma :- Bone cancer ,common in children ,teens; aggressive ,often in long bones like femur.
- Soft tissue sarcoma:_ From fat,muscle, or blood vessels;rare,can appear anywhere in body.
C) Leukemias (blood cancer)
Cancers of blood -forming tissues in bone marrow ,leading to abnormal white cell overproduction.
- Acute lymphoblastic leukemia (ALL):- Rapid overproduction of immature white blood cells ; hits kids most
- Chronic myeloid leukemia (CML) :- Slow buildup of abnormal white cells; treatable with targeted drugs like imatinib
D) Lymphomas (lymphatic system)
Lymphomas affect lymphocytes ,while multiple myeloma targets plasma celle producing antibodies ; both disrupt immune function.
- Hodgkin lymphoma:- Cancer of lymph nodes; Reed-Sternberg cells hallmark;highly curable.
- Non-Hodgkin lymphoma:-Diverse group affecting lymphocytes; varies from indolent to aggressive.
E) Central Nervous System Cancers
Gliomas (from glial cells) and meningiomas originate in brain /spinal cord tissues, often aggressive due to the blood brain barrier.
- Glioblastoma :- Aggressive brain tumor from glial cells; fast -growing ,hard to treat.
- Meningioma:- From brain/Spinal cord membranes ;often benign butcan be malignant.
Cancer encompasses over 100 distinct diseases classified primarily by the tissue or cell type from which they originate ,with malignant cells capable of invading nearby structures and metastasizing.Early detection via screening improves outcomes.
The difference between benign and malignant tumors
Benign and malignant tumours differ fundamentally in their cellular behavour, genetic alternations ,growth patterns and potential to harm the body.
A) Growth and Structure
- Benign tumors grow slowly with well- defined borders and organized cells resembling normal tissue ; they remain encapsulated ,compressing but not invading surrounding structures.
- Malignant tumors expand rapidly with irregular , infiltrative edges, disorganized anaplastic cells that lack differentiation ,and fewer cell to cell connections.
B) Invasion and Metastasis
Benign tumors stay localized without invading nearby tissues or spreading via blood /lymphatics, often curable by surgical removal.
Malignant tumors invade adjacent areas and metastasize distantly , forming new tumors through angiogenesis promotion and immune evasion.
C) Genetic Basis
Benign tumors typically arise from 2 to 3 mutations ,retaining some regulatory controls
Malignant ones accumulate 4+ key mutations (e.g. in tumor suppressors ) plus progression mutations ,disrupting apoptosis , proliferation ,and DNA repair
Symptoms
Common Symptoms suggesting cancer presence include unexplained weight loss ( over 10 pounds) loss of appetite , extreme tiredness, night sweats ,recurrent fever ,persistent fatigue ,lumps or swelling and abnormal bleeding , though these can stem from other causes and require medical evaluation.
